I bet there's some hormonal release reason to do it before or after...but I forget which is better. Like if you jack-off right before does it release chemicals that help you lift better? Good question...wish I had the answer.

The buildup and process of going to the gym, my gym at least, is very sexual. To do so beforehand, well, it depletes you of some of that energy, but holding on to your "chi" sustains this energy throughout your workout.

I also think that on a primal level, battling for a sexual partner is equivalent to a good "tear apart" workout. With spoils to follow.

...although sometimes I'm so exhausted after. Maybe because I'm also starving, so I go eat straight after a WO?